82 650GL breaks up after 5500 RPM

[mhobryan]

Well that was tedious... since all but one of my valves were tight, I had to remove original shim, replace with a smaller shim, recheck gap, record gap measurement, then replace again b/c I needed my small shim. After doing this for 3 valves, remember reading on here about putting in a quarter as a place holder so I could turn w/o ruining the buckets or cam lobes. This seemed to work.

While I was at it, did my other GS650G - valves were in much better specs. only 3 out of tolerance, 2 tight, one loose. Between the two bikes, will have to order 5 shims, plus one extra (used the zip tie and got a really fat remeasure, so thinking may have knocked some carbon loose, so ordering one add'l thinner one)

Will be placing my order with Z enterprises today. Mostly need shims in the 2.5 to 2.65 range.

Cheers,
Mike

[koolaid_kid]

Why don't you join the shim club here at GSR?

[mhobryan]

I will join the club; and will have about 3 left over to contribute. - I just want to get these guys DONE. Want to have them ready to put on craigslist once the weather breaks, and then I can get an 850G

[tom203]

Since you have a collection of soon-to-be-for-sale gs650G's . connect with that guy looking for one (anywhere) on bikes wanted for sale forum.

[mhobryan]

Okay - Put the new shims in, rechecked the valves, had two that were on the loose side after I put in the new shims; everything else is w/in spec. Figured slightly loose was better than too tight. I've also readjusted mixture screws, and rebalanced the carbs (again). Idles and runs smoother, and also seems to start much easier hot.

But, it is still breaking up past 5,500 rpm. It will do this both under load, and no load. Under no load it will rev higher, but you can hear it breaking up... I strongly suspect ignition because of this.

I know the R/R needs to be replaced (it's over charging at above 3k RPMs) I will order one next paycheck. Could a failed/failing R/R cause this? What else would cause this symptom?

EDIT: Side note be sure to store your carb sync tool inside, esp. if you live in colder climates, and have one that doesn't use mercury. The liquid is freezable....took me a second to figure out why the liquid in two of the four calibration tubes wasn't moving - a few minutes in front of the heater fixed that.

[tom203]

Since you got 2 gs650 (both shafties ?), swap the ignitors and see what happens.

[JTGS850GL]

Check the connections to the coils. Very common for them to get dirty and create a voltage drop at the coil. Check plug gap as well. Too large a gap and you could be getting flame blowout. May also need to go up one on the main jet. Adjusting the pilot screws wont help you much at the higher throttle turns. Does sound like you're getting closer though.

[mhobryan]

Plugs are gapped correctly - checked and regapped last month.

If it didn't sputter/break up when I revved in a no load condition (e.g. in neutral) then I would agree, all signals would point to inefficient fuel flow and bigger jets. With no load on the engine, there should be plenty of fuel flow to get it to rev past 5.5k, yet it breaks up.

Not saying it doesn't need bigger jets, but don't think that is the root cause of this problem/symptom. It used to rev past 5.5k when it had both pods and the 4-1 header. I've put the stock air box back on it, so if anything it should have helped the situation.

I will check the coils and test/swap the ignitor.

[mhobryan]

hmmm....cleaning the spades on the coils helped - didn't cure it but if I let off the throttle some she'd clear her throat and would rev up to 7k (as high as i could go in 2nd on city streets)...

[nejeff]

hmmm....cleaning the spades on the coils helped - didn't cure it but if I let off the throttle some she'd clear her throat and would rev up to 7k (as high as i could go in 2nd on city streets)...

Keep cleaning connections and while your at it go ahead and do the coil relay mod for good measure

[mhobryan]

Keep cleaning connections and while your at it go ahead and do the coil relay mod for good measure

I cleaned a bunch last fall (all fuses and connections, battery terminals, and grounds) but haven't got to all of them yet. Waiting a bit before I buy a Polaris R/R (mine's toast - charging at 16v at higher RPMs).

I've probably got a good 20-30 hours into this bike already...it's been a slow process. Want to get it running reliable enough so I can flip it ... and buy an 850G ... and start the whole process all over again.

[barnbiketom]

your igniter is a ticking time bomb..with 16 volts

[tkent02]

I've probably got a good 20-30 hours into this bike already...it's been a slow process. Want to get it running reliable enough so I can flip it ... and buy an 850G ... and start the whole process all over again.

Then just buy a cheap used regulator that still works. Having fancy new one won't help you flip it any better.

[mhobryan]

Then just buy a cheap used regulator that still works. Having fancy new one won't help you flip it any better.

I realize it is just an L

But, I hear you - my concern with buying a used one is that it will be over charging too (hey! it came off a 'running' bike!). A new Polaris is about $70ish - used one will probably cost me $20 or so; and I probably have a 50/50 chance at best it will be regulating correctly. $50 is cheap piece of mind for me, and I know the problem has been fixed. Besides, it's kinda a pay-it-forward kind of thing.... most likely some new rider will end up buying it and at least I know they should have a trouble free riding season.

[mhobryan]

Problem resolved. I put the pods back on and she runs great! The PO said he had rejetted for the pipes and pods, however, I had assumed he hadn't when I pulled out one of the main jets and it was a stock size. I bought a used airbox off of fleabay and installed it this spring.

What clued me in, was removing the air filter increased the usable RPM range to 7k, adding it back it in dropped to 5.5k.

Bike has been pretty much completely gone through at this point, so feel comfortable selling it.

Thanks for everyone's help.